Add explanation for why on earth we have the same function repeated four times

Add linux_dirent struct block to PTREGS hook_getdents()

Fix for kernel versions <4.17 ...

The old linux_dirent struct isn't in the kernel headers anymore - even on 16.04
Declaring it manually allows us to copy the structure into kernel memory and dereference it later

3.4: tabs to spaces

working on support for < 4.17

update to use ftrace

fix section number

add directory hiding